It's early evening in a quiet central Tokyo neighbourhood, and mom of three Asako Saito is chatting with her kids about their day. Looking at them in the living room of their fifth floor apartment, it's hard to see any sign of the growing worry lurking in the backs of their minds.

"We're scared, obviously, and sort of shell-shocked at how things are actually turning out," says Saito.

She tries to hide it from her children, but Saito says she worries that the growing North Korean nuclear crisis will move past sabre rattling to something much worse.

Asako Saito sits with her three children in Tokyo. Saito is growing increasingly worried about what may happen if the North Korean nuclear crisis continues to heat up. (Adam Walsh/CBC)

"I didn't think it would get this far," she says in her slightly British lilt. "I'm just praying that the leaders are smart enough to avoid any kind of a real clash between, you know, our countries or the States."

Pyongyang is threatening to keep firing missiles in Japan's direction or beyond, and those missiles could soon be much more destructive. On Sept. 3, North Korea detonated what it says was a hydrogen bomb that it claims is small enough to fit onto an intercontinental missile.

In response to Pyongyang's latest nuclear test, the UN Security Council unanimously passed further sanctions targeting the country on Monday. The watered-down resolution limits oil imports and bans textile exports, which are a significant source of income for the country.

This image distributed by the North Korean government shows North Korean leader Kim Jong-un inspecting equipment at an undisclosed location. North Korea says that its Sept. 3 test was a hydrogen bomb ready to be mounted on an ICBM. (Korean Central News Agency/Korea News Service/Associated Press)

It's been an eventful 18 months on the Korean peninsula and the surrounding region. North Korean leader Kim Jong-un launched several missiles into the Sea of Japan, and the war of words between North Korea and the United States has been heated.

At the end of August, tensions escalated. For the first time, North Korea blasted a ballistic missile over Japan and into the Pacific Ocean. The country's emergency alert blared on millions of cellphones, and sirens sounded across Japan's north, bringing many residents to the realization they could no longer ignore their increasingly belligerent neighbour.

Booming business

North Korea's threats have meant a booming business for an industry that many associate with the Cold War: bomb shelters.

Nobuko Oribe sells shelters meant to protect people from a nuclear blast and its aftermath.

A man in Tokyo walks in front of a huge monitor showing news of a North Korean missile test. (Toru Hanai/Reuters)

"Two weeks is the world standard. So, you can live healthy enough after the bomb explosion," says Oribe in Japanese when describing how her shelters work.

Oribe's shelters don't come cheap. Installing one during the construction phase of a house will run about $110,000. If it's a retrofit to an existing home, the cost jumps to about $280,000.

Despite the price, orders are up. Oribe says she sold 38 shelters last year, and so far this year, she has already closed deals for about 80 per cent more.

But while she's happy that business is good, she is unnerved by what's been going on and uncertain about what approach her country should take.

Hiroshima atomic bomb survivor Koko Kondo has dedicated her life to warning the world about the danger of nuclear weapons. (Koko Kondo)

"That's what's scary. What if they actually use nuclear weapons on countries such as Japan, and what should we do if that happens?" she says.

Koko Kondo, now 72, was eight months old when the Americans unleashed an atomic bomb on her city of Hiroshima at the end of the Second World War. Her family is featured in one of the definitive accounts of the devastation, Hiroshima, by John Hersey.

Kondo says many atomic bomb survivors are frustrated by the recent news from the Korean Peninsula. She is shaken to her core when she hears reports of the estimated strength of North Korea's most recent nuclear test.

"I heard just the other day, [it was] what, 10 times more [powerful] than the Hiroshima bomb," she says. "It's so scaring me ... If today's bomb is much, much, much stronger, not like Hiroshima and Nagasaki, maybe this whole world is going to go."

Kondo wants to make sure both U.S. President Donald Trump and Kim realize the massive potential for suffering from any possible war.

"It's so sad, you know. So sad," she sighs heavily. "We are not learning anything!"

Nuclear crisis fallout

While Oribe's shelter sales are rising, other businesses are being put at risk by the political tensions and uncertainty.

"People have been choosing Japan because it feels safe. It is a safe country," he says outside a hipster cafe in a leafy part of Tokyo. "They really enjoy that kind of sense that they can really relax here. And I think if there are these kind of worries, then that advantage goes away."

So far, clients are still booking. But Spreckley brings up the 2011 earthquake and tsunami, which set off a meltdown at the Fukushima Daiichi Nuclear Power Plant and caused Spreckley's business to evaporate. He thinks bookings could soon slow again, so he's looking to expand into other countries.

Asako Saito says she's praying North Korea's nuclear tests are political posturing rather than preparations for an actual war. (Adam Walsh/CBC)

"Good times are really good, but everything can fall apart very quickly with an earthquake or something else like what's happening now," he says.

"At the time, some of the experts did say that the meltdown was imminent and the radiation might be spilling out," she says. "So, we took extreme measures, and we moved out of Tokyo to the western part [of the country], to Kyoto, actually."

From there, it was on to England to stay with her brother until her family felt it was safe to return.

For now, she isn't contemplating leaving Japan because of the North Korea situation. When asked what it would take to persuade her to pick up and move again, Saito said she isn't sure.

"Um ... I don't know. If either side declares war, obviously, I would. But is that how wars start nowadays?" she wonders, with a bit of a laugh. "I really have no idea. It's hard to say."

After a pause, she adds a chilling thought.

"You know, if it happens I don't think there is anything I can do to protect my family."